What does Mittenwool tell Silas about the ghosts in the bog?

Mittenwool tells Silas that the ghosts in the bog do not mean Silas any harm. They are simply passing through, just as Silas is passing through. Mittenwool is not sure if they linger in the bog because the ground holds some meaning to them. He believes that the ghosts will move on when they are ready. Mittenwool tells Silas that they will not come and bother him in the night.